ELB health checks for freshly launched EC2 instances not working

I'm trying to manually set up a load balanced environment using EC2. My instances are reachable via SSH and ping. However, as soon as I put them inside a load balancer, the instances are not able to pass the load balancer's health checks.

• I've tried following the Troubleshooting Elastic Load Balancing guide. Connecting to any instance via telnet from another instance inside the same VPC does not work.
• Executing telnet localhost 25 inside an instance seems to work.
• The instances run Amazon Linux.
• The health check happens via TCP to port 80.
• The load balancer and the instances are in the same security group.
• I've already loosened up all security group settings and allowed communication via all ports, all members of all groups are able to ssh / ping each other.
• The problems appear right after launch, no matter if I've set up the instances with the software I want them to run or left them untouched.

What else should I try? Thanks!

Solution 1:

Got it working by directing the health check to port 22.